Castor axle having noise suppression function

ABSTRACT

A chair includes a leg having a mounting hole, a castor having an end portion provided with an axle mounted in the mounting hole of the leg, and a substantially S-shaped snap ring mounted in the annular groove of the axle and rested on a peripheral wall of the mounting hole of the leg. Thus, the S-shaped snap ring is enclosed around the peripheral wall of the annular groove of the axle and rested between the upper wall and the lower wall of the annular groove, so that the S-shaped snap ring will not slip in the annular groove of the axle to prevent from producing noise due to friction between the axle of the castor and the leg during movement of the castor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a castor axle and, more particularly, to a castor axle for a chair.

2. Description of the Related Art

A conventional chair in accordance with the prior art shown in FIG. 4 comprises a leg 12 having an inside formed with a mounting hole 120, a castor 10 pivotally mounted on the leg 12 and having an end portion provided with an axle 11 mounted in the mounting hole 120 of the leg 12 and having an upper end formed with an annular groove 110, and a substantially C-shaped snap ring 13 mounted in the annular groove 110 of the axle 11 and rested on the peripheral wall of the mounting hole 120 of the leg 12.

However, the C-shaped snap ring 13 slips in the annular groove 110 of the axle 11 during movement of the castor 10, so that the C-shaped snap ring 13 easily rubs the peripheral wall of the mounting hole 120 of the leg 12, thereby producing noise due to friction between the C-shaped snap ring 13 and the leg 12 during movement of the castor 10. In addition, the C-shaped snap ring 13 is not compressible elastically upward and downward, so that the contact face between the C-shaped snap ring 13 and the annular groove 110 of the axle 10 is changed to a contact point by pressing of the gravity force during a long-term utilization to form a clearance between the C-shaped snap ring 13 and the annular groove 110 of the axle 10, thereby producing noise due to hit between the C-shaped snap ring 13 and the annular groove 110 of the axle 10 when the user is seated on the chair.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a chair, comprising a leg having an inside formed with a mounting hole, a castor pivotally mounted on the leg and having an end portion provided with an axle mounted in the mounting hole of the leg, the axle of the castor having an upper end formed with an annular groove, and a substantially S-shaped snap ring mounted in the annular groove of the axle and rested on a peripheral wall of the mounting hole of the leg.

The primary objective of the present invention is to provide a castor axle having a noise suppression function.

Another objective of the present invention is to provide a chair, wherein the S-shaped snap ring has two end portions rested on the upper wall and the lower wall of the annular groove of the axle respectively and has an outer periphery rested on the peripheral wall of the mounting hole of the leg elastically, so that the axle of the castor is connected to the leg rigidly and stably.

A further objective of the present invention is to provide a chair, wherein the S-shaped snap ring having a curved bending shape is enclosed around a peripheral wall of the annular groove of the axle and rested between the upper wall and the lower wall of the annular groove, so that the S-shaped snap ring will not slip in the annular groove of the axle to prevent from producing noise due to friction between the S-shaped snap ring and the leg during movement of the castor.

A further objective of the present invention is to provide a chair, wherein the S-shaped snap ring has a curved bending shape and is compressible elastically upward and downward, so that the contact face between the S-shaped snap ring and the annular groove of the axle is not changed by pressing of the gravity force during a long-term utilization, thereby enhancing the lifetime of the S-shaped snap ring.

Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a partially perspective view of a chair in accordance with the preferred embodiment of the present invention.

FIG. 2 is an exploded perspective view of the chair as shown in FIG. 1.

FIG. 3 is a partially plan cross-sectional view of the chair as shown in FIG. 1.

FIG. 4 is a partially plan cross-sectional view of a conventional chair in accordance with the prior art.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and initially to FIG. 1, a chair in accordance with the preferred embodiment of the present invention comprises a leg 2, and a castor 3 pivotally mounted on the leg 2.

Referring to FIGS. 1-3, the leg 2 has an inside formed with a mounting hole 20. The castor 3 has an end portion provided with an axle 30 mounted in the mounting hole 20 of the leg 2. The axle 30 of the castor 3 has an upper end formed with an annular groove 300 for mounting a substantially S-shaped snap ring 4 which is rested on a peripheral wall of the mounting hole 20 of the leg 2. The annular groove 300 of the axle 30 has an upper wall 301 and a lower wall 302. The S-shaped snap ring 4 has a curved bending shape. The S-shaped snap ring 4 is snapped into the annular groove 300 of the axle 30 and has two end portions 40 rested on the upper wall 301 and the lower wall 302 of the annular groove 300 of the axle 30 respectively. Each of the two end portions 40 of the S-shaped snap ring 4 has a curved bending shape.

Accordingly, the S-shaped snap ring 4 has two end portions 40 rested on the upper wall 301 and the lower wall 302 of the annular groove 300 of the axle 30 respectively and has an outer periphery rested on the peripheral wall of the mounting hole 20 of the leg 2 elastically, so that the axle 30 of the castor 3 is connected to the leg 2 rigidly and stably. In addition, the S-shaped snap ring 4 having a curved bending shape is enclosed around a peripheral wall of the annular groove 300 of the axle. 30 and rested between the upper wall 301 and the lower wall 302 of the annular groove 300, so that the S-shaped snap ring 4 will not slip in the annular groove 300 of the axle 30 to prevent from producing noise due to friction between the S-shaped snap ring 4 and the leg 2 during movement of the castor 3. Further, the S-shaped snap ring 4 has a curved bending shape and is compressible elastically upward and downward, so that the contact face between the S-shaped snap ring 4 and the annular groove 300 of the axle 30 is not changed by pressing of the gravity force during a long-term utilization, thereby enhancing the lifetime of the S-shaped snap ring 4.

Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention. 

1. A chair, comprising: a leg having an inside formed with a mounting hole; a castor pivotally mounted on the leg and having an end portion provided with an axle mounted in the mounting hole of the leg, the axle of the castor having an upper end formed with an annular groove; a substantially S-shaped snap ring mounted in the annular groove of the axle and rested on a peripheral wall of the mounting hole of the leg.
 2. The chair in accordance with claim 1, wherein the annular groove of the axle has an upper wall and a lower wall, and the S-shaped snap ring has two end portions rested on the upper wall and the lower wall of the annular groove of the axle respectively.
 3. The chair in accordance with claim 2, wherein each of the two end portions of the S-shaped snap ring has a curved bending shape.
 4. The chair in accordance with claim 1, wherein the S-shaped snap ring has a curved bending shape.
 5. The chair in accordance with claim 1, wherein the S-shaped snap ring is snapped into the annular groove of the axle.
 6. The chair in accordance with claim 1, wherein the S-shaped snap ring has an outer periphery rested on the peripheral wall of the mounting hole of the leg elastically.
 7. The chair in accordance with claim 1, wherein the S-shaped snap ring is enclosed around a peripheral wall of the annular groove of the axle and rested between the upper wall and the lower wall of the annular groove, so that the S-shaped snap ring will not slip in the annular groove of the axle.
 8. The chair in accordance with claim 1, wherein the S-shaped snap ring is compressible elastically upward and downward. 